Process for the preparation of aryl-1,1,2,2-tetrafluoroethyl ethers

ABSTRACT

Phenols react with tetrafluoroethylene at normal or reduced pressure when using about 0.05 to about 0.5 mole of an alkali metal hydroxide per each equivalent of phenolic hydroxy group as a catalyst and a water-miscible polar inert solvent to yield aryl-1,1,2,2-tetrafluoroethyl ethers. The products are useful as intermediates in the synthesis of dyestuffs and plant-protecting agents.

United States Patent 1 Rebsdat et al.

[ Dec. 16, 1975 PROCESS FOR THE PREPARATION OFARYL-l,l,2,2-TETRAFLUOROETHYL ETHERS [75] Inventors: Siegfried Rebsdat,Altotting; I-Ielmut Hahn, Burghausen, both of Germany [73] Assignee:I-Ioechst Aktiengesellschaft,

Frankfurt am Main, Germany [22] Filed: June 14, 1971 [21] Appl. No.:152,600

[30] Foreign Application Priority Data June 16, 1970 Germany 2029556[52] US. Cl.. 260/247.7 C; 260/293.83; 260/562 A", 260/574; 260/575;260/600; 260/613 D; 260/612 R", 260/612 D [51] Int. Cl. C07C 41/06 [58]Field of Search 260/612, 562, 571, 574, 260/575, 247.7, 293.83, 600

[ 56] References Cited FOREIGN PATENTS OR APPLICATIONS 2.005.876 l2/l969France 260/612 Primary Examiner-Harry I. Moatz Attorney, Agent, orFirmConnolly and Hutz [57] ABSTRACT 9 Claims, 1 Drawing Figure U.S.Patent Dec. 16, 1975 3,926,989

A P A 10 "\5 INVENTORS SIEGFRIED REBSDAT HELMUT HAHN ATTORNEYS PROCESSFOR THE PREPARATION or- ARYL-l,1,2,2-TETRAFLUOROETHYL ETHERS The presentinvention relates to a process for the 5 preparation ofaryl-l,1,2,2-tetrafiuoroethylethers by reacting phenols withtetrafluoroethylene in organic solvents in the presence of alkalinecatalysts,"comprising contacting a solution of about 5 to about 50percent by weight of the phenol in water-miscible, polar solvents inerttowards tetrafluoroethylene under the reaction conditions. preferablydimethylformamide, hexamethyl-phosphoric acid trisamide ofdimethylsulfoxide, in the presence of about 0.05 to about 0.5 mole of analkali metal hydroxide per equivalent of phenol at normal pressure orslightly reduced pressure and temperatures of from about 50 to about150C with tetrafluoroethylene.

From US. Patent specification it is known thatphenyl-l,l,2,2-tetrafluoroethyl ether may be prepared by addition oftetrafluoroethylene to phenols. In the single example concerning phenolthe reaction is carried out in the course of about 12 hours at 100Cunder pressure in the autoclave in the presence of metallic sodium ascatalyst and benzene as solvent. The phenyl-1,1 ,2,2- tetrafluoroethylether is obtained with a yield of 4.6 percent.

D. C. England et al. (J. Am. Chem. Soc. 82, 5116 2122 (1960)) have foundan improvement to this process, using dimethylformamide or dioxan assolvents, the operation being carried out under pressure (2-2.7atmospheres gauge) and at temperatures of from 60 100C. Instead ofmetallic sodium, W. A. Sheppard (Journal of Organic Chemistry 29, 1 11(1964)) employed in this process sodium hydride in dispersed form.

The reaction of sodium phenolate with tetrafluoroethylene indimethylformamide under a relatively high pressure the sodium phenolatebeing formed in situ from phenol and sodium, is described in US. Pat.No. 3,277,068.

From Belgian Patent specification No. 741,243 it is known that phenolsmay be reacted under pressure with tetrafluoroethylene in the presenceof alkali metal hydroxides or alkali metal phenolates, if a certainamount of water is present and a certain critical molar ratio oftetrafluoroethylene to phenol is maintained. In the Belgian Patentspecifications Nos. 691,603 and 691,604 there is also mentioned thereaction of nitroor aminophenols with tetrafluoroethylene under pressurein the presence of alkali metal or alkaline earth metal hydroxides,sodium hydride or sodium 'rnethoxide as catalyst and dimethylformamideor dioxan as solvents.

All these processes have the disadvantage that the operation must becarried out under pressure, which takes expensive security measures dueto the easy explosive decomposition of tetrafluoroethylene.

It has therefore been desirable to find a process which may be performedwithout pressure and with a catalyst easily to be handled and whichrenders superfluous the use of anhydrous solvents. Experiments of thistype have hitherto been fruitless. Thus, J. W. C. Crawford (J. Chem.Soc. 1967, 2396) has stated that phenol in the presence of sodiumphenolate formed in situ from sodium metal and phenol anddimethylsulfoxide or dimethylformamide does not react withtetrafluoroethylene at normal pressure.

It has therefore been surprising that tetrafluoroethylene easily reactswitih phenols at normal pressure to form the correspondingaryl-tetratluoroethyl ethers in good yields. if instead of the metallicsodium or sodium hydride an alkali metal hydroxide is used as catalystand if water-miscible, polar solvents, preferably dimethylformamide,hexamethyl-phosphoric acid trisamide or .dimethylsulfoxide are used. Thereaction proceeds so easily that the reaction may be carried out even ata slightly reduced pressure.

As phenolic starting compounds there may also be considered besidesphenol mono-, diand trisubstituted phenols. As substituents in thephenyl nucleus there are especially preferred: straight-chain orbranched alkyl groups having preferably up to 20, especially up to 4carbon atoms, hydroxy, alkoxy groups having up to 6, especially up to 4carbon atoms, formyl, amino, alkylamino and dialkylamino-groups havingpreferably up to 4 carbon atoms in each alkyl moiety, as well as thepiperidino and the morpholino group and alkanoylamino groups having upto 6 carbon atoms, especially acetamino groups. Furthermore there may beused polynuclear phenols, such as the naphthols.

The solvent is not necessarily anhydrous and may be used withoutdifficulty in a technical quality. The phenol is dissolved in thissolvent in a concentration of about 5 to about 50 percent by weight,preferably about 15 to about 20 percent by weight. As catalysts thereare used alkali metal hydroxides, preferably potassium hydroxide, inamounts of from about 0.05 to about 0.5 preferably about 0.15 to about0.3 mole, per equivalent of phenol, which are dissolved in the phenolicsolution. One fequivalent of phenol is a mole of phenol divided by thenumber of the phenolic hydroxy groups in the phenol molecule. Thementioned amounts of catalyst have therefore to be referred to mole ofphenolic hydroxy groups.

The reaction may be carried out by passing tetrafluoroethylene over theintensively stirred reaction mixture heated to about 50 to about 150C,preferably to 130C. The reaction proceeds more'rapidly, if the phenolicsolution is passed over a heated packed column and thetetrafluoroethylene is introduced into this column at normal pressure,where it is absorbed.

The reaction speed is different for the'different phenols. In many casesthe reaction is exothermic; it is completed, if the absorption oftetrafluoroethylene is finished.

The reaction products are usually isolated by distillation of theobtained mixtures, the solvent being recovered or by treating thereaction mixture with water; the reaction product is precipitatedand thesolvent as well as the catalyst are transferred into the aqueous phase.

The following Examples illustratethe invention.

EXAMPLE 1 The o-sec.-butylphenol was reacted'with tetrafluoroethylene inthe device represented by FIG. 1. For this purpose, g (0.5 mole) ofo-sec.-butylphenol were dissolved in 240 g of dimethylformamide and 7 g(0.125 mole) of KOH were added. The whole was stirred until a solutionwas obtained, heating being optionally necessary. The resulting solutionwas filled into the flask (l) of the reaction device. The flask l andthe column (2) were rinsed with nitrogen from the pressure vessel (3)and then with tetrafluoroethylene from the stock vessel (4) over thefeed lines (5) and (6). Then the flask (l) (by means of the heating bath3 (7)) and the column (2) were heated to 90C. The pump (8) was started.so that the solution trickled over the feed line (9) through the column(2). The inner tion of tetrafluorocthylene was completed.

The reaction product was obtained with a 99 percent purity byprecipitating with water. drying with Na- ,SO

temperature regulated by the thermostat (l) and subsequentfractionation. (ll g (92 percent) of amounted to 87C. After starting thepump (8). the 5 l-tetrafluoroethoxy-2-sec.-butyl-benzene. boiling pointconsumption of tetrafluoroethylene began immedi- 94C.n,,-"" 1.4314).ately. The levelling vessel was so adjusted that the pres- The reactionproducts of other phenols with tetraflusure was not far below normalpressure. (12) is an oroethylene obtained in analogous way are listed inoutlet valve. By the exothermic reaction. the tempera- Table l asExamples 2 to 18. ture Increased to 100C. After 18 minutes the absorp-Table 1 Example Product charge reaction reaction yield boiling melt-Phenol catalyst solvent temperature time 71 point ing No. min.) of the"Cl point (mole) (mole) lg) (0C) hours theory mm (Cl c F 2 c F 2 H 2 1.0KOHHLZ) DMF (2501 94-95 75. 80.5

34 3 0.5 KOHHHZS) DMSO(24()) 93 94 0 73.3

0c r 2 c F 2H 31 1|: 4 0.5 KOHHLIZS) DMF (240) 93-100 0 99.5 I:

cr ,CF2H

m n-92.5 5 0.5 K0H 0.25 DMF (240) 86-93 I 6| l5 oc F 2 CF 2 H I) [06-1086 0.5 KOHHLZS) DMF (:40) as: 0 75 ll OCF ,cF H

cgu 1x 94 7 CH 0.5 KOHHLIZS) DMF (240) 87-l00 0 02 20 33 -102 8 0.5K0Ht0.25l DMF (240) 91-97 0 67 12 F 2 c r H 00 -49 I03 9 0.5 KOH (0.25)DMF (240) 94- 1 13 F 2 CF 2H 57 (al 10 0.5 K0H(0.|25l DMF (240) 4e1 57 081 1:

ocF 2 c F Table l-continued Example Product charge reaction reactionyield boiling melt- Phenol catalyst solvent temperature time '71 pointing Nomin.) of the Cl point (mole) (mole) (g) (C) hours theory mm 1C! F2. F 2 0.5 KOH(0.l..5) DMF (-40) 85 9h 0 89.4 l3

3! l2 0 5 KOH(0.lZ5) DMSO( 270) 86- l00 63.7

51 13 0.5 KOHHHZS) HPTA( 255) 83-78 0 s33 Sl 14 II 0.5 NaOHtOJZS) DMF(240) 93 0 69.5

27 l5 0.5 K CO HLIZS) DMF (240) 90-91 I 76 CF JZF H 4 97-400 l6 OCF CF H0.5 KOH (0.25) DMF (240) 88-90 2 83.24 3'.

C F 2 C F 2 H 32 17 0.5 KOH(0.lZ5l DMF (240) 93- 95 0 99.6 l l7 H CO C H3 OC F 2 CF H ()0 l8 0.5 KOHHLIZS) HPTA 255) 60-54 4 68.6 2)

DMF Dimethylformumide DMSO Dimethylsulfoxide HPTA Hexamcthyl-phosphoricacid trisamide We claim:

1. ln a process for the preparation of an aryl-l, 1,2.Z-tetra-fluoroethyl ether by reacting a phenol with tetrafluorethylenein an organic solvent in the presence of an alkaline catalyst atelevated temperatures, the improvement comprising reacting a phenoliccompound selected from thee group consisting of phenol, naphthol andphenol substituted by l to 3 substituents selected from the groupconsisting of alkyl of l to carbon atoms, alkoxy of l to 6 carbon atoms,hydroxy, formyl. amino. monoalkylamino of l to 4 carbon atoms,dialkylamino of l to 4 carbon atoms in each alkyl moiety. piperidino.morpholino and alkanoylamino of l to 5 carbon atoms in the a'lkanemoiety. with tetrafluoroethylene in a water-miscible polar inert solventwith about 0.05 to about 0.5 mol of potassium hydroxide per eachequivalent of phenolic hydroxy group at a temperature of about to about150C and a pressure varying between atmospheric pressure and slightlysubatmospheric pressure.

2. The process as claimed in claim 1, wherein the phenolic compound isphenol. naphthol or phenol substituted by lower alkyl. amino. formyl,hydroxy or acetamino.

3. The process as claimed in claim 1, wherein the solvent is dimethylformamide.

4. The process as claimed in claim 1, wherein the solvent isdimethylsulfoxide.

5. The process as claimed in cliam I, wherein the solvent is phosphoricacid tris-(dimethylamide).

6. The process as claimed in claim 1, wherein the reaction mixturecontains about 10 to about 30 percent by weight of phenolic compound.

7. The process as claimed in claim I, wherein the reaction mixturecontains about 1 5 to about 20 percent by weight of phenolic compound.

8. The process as claimed in claim 1, wherein the alkali metal hydroxideis used in an amount of about 0.] to 0.3 mol per each equivalent ofphenolic hydroxy group.

9. The process as claimed in claim 1, wherein the temperature is in therange of about to about C.

1. IN A PROCESS FOR THE PREPARATION OF AN ARYL-1,2,2-TETRAFLUOROETHYLETHER BY REACTING A PHENOL WITH TETRAFLUORETHYLENE IN AN ORGANIC SOLVENTIN THE PRESENCE OF AN ALKALINE CATALYST AT ELEVATED TEMPERATURES, THEIMMPROVEMENT COMPRISING REACTING A PHENOLIC COMPOUND SELECTED FROM THEGROUP CONSISTING OF PHENOL, NAPHTHOL AND PHENOL SUBSTITUTED BY 1 TO 3SUBSTITUTENTS SELECTED FROM THE GROUP CONSISTING OF ALKYL OF 1 TO 20CARBON ATOMS, ALKOXY OF 1 TO 6 CARBON ATOMS, HYDROXY, FORMYL, AMINO,MONOALKYLAMINO OF 1 TO 4 CARBON ATOMS, DIALKYLAMINO OF 1 TO 4 CARBONATOMS IN ACH ALKYL MOIETY, PIPERIDINO, MORPHOLINO AND ALKANOYLAMINO OF 1TO 5 CARBON ATOMS IN THE ALKANE MOIETY, WITH TETRAFLUOROETHYLENE IN AWATER-MISCIBLE POLAR INERT SOLVENT WITH ABOUT 0.05 TO ABOUT 0.5 MOL OFPOTASSIUM HYDROXIDE PER EACH EQUIVALENT OF PHENOLIC HYDROXY GROUP AT ATEMPERATURE OF ABOUT 50* TO ABOUT 150*C AND A PRESSURE VARYING BETWEENATMOSHERIC PRESSURE AND SLIGHTLY SUBATMOSPHERIC PRESSURE.
 2. The processas claimed in claim 1, wherein the phenolic compound is phenol, naphtholor phenol substituted by lower alkyl, amino, formyl, hydroxy oracetamino.
 3. The process as claimed in claim 1, wherein the solvent isdimethyl formamide.
 4. The process as claimed in claim 1, wherein thesolvent is dimethylsulfoxide.
 5. The process as claimed in cliam 1,wherein the solvent is phosphoric acid tris-(dimethylamide).
 6. Theprocess as claimed in claim 1, wherein the reaction mixture containsabout 10 to about 30 percent by weight of phenolic compound.
 7. Theprocess as claimed in claim 1, wherein the reaction mixture containsabout 15 to about 20 percent by weight of phenolic compound.
 8. Theprocess as claimed in claim 1, wherein the alkali metal hydroxide isused in an amount of about 0.1 to 0.3 mol per each equivalent ofphenolic hydroxy group.
 9. The process as claimed in claim 1, whereinthe temperature is in the range of about 70* to about 130* C.